JPS60169794A - High-temperature gas furnace using spherical fuel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a high temperature gas furnace using spherical fuel consisting of fuel pellets embedded within a graphite matrix, wherein the coach ink of the fuel pellets forms a first barrier and the graphite matrix A prestressed concrete pressure vessel is provided as a pressure-tight containment vessel, forming a second barrier, the plurality of barriers preventing the diffusion of fission products, and surrounding the high temperature gas reactor, the pressure vessel having a metal liner inside. This invention relates to a high-temperature gas furnace having an internal space lined with power and equipped with an aerodynamic mechanism.

[Description of prior art]

In the structure of a conventional nuclear reactor, the pressure-resistant container constituting the primary coolant passage has a pressure-resistant and sealing effect, suppressing the diffusion of nuclear fission products to below a permissible value under normal or abnormal conditions.

In some nuclear reactors, the secondary coolant passages are formed by pressure tanks made of steel, which have drawbacks in pressure resistance and sealing. In the event of an accident with loss of pressure resistance comparable to a catastrophic failure of this pressure tank, various other measures for this reactor (i.e. basic safety, quality control and work monitoring measures) should be taken. Safety is ensured by

In other words, a safety tank surrounding this steel pressure tank is required as a backup barrier against the dispersion of fission products in the event that this pressure vessel ruptures and leaks. Ensure reliability of container sealing action. That is, because the concentration of radioactive material in the reactor cooling medium is high, the above-mentioned safety tank is necessary, especially as an extra barrier against loss of sealing action. Such a nuclear reactor is described, for example, in German Federal Patent Publication No. 23 15
31B and German Federal Patent Publication No. 231531
It is shown in No.9.

In high-temperature gas reactors using spherical fuel, apart from the two barriers already mentioned in the fuel, two further barriers to the diffusion of fission products are provided. This barrier consists of the reactor pressure tank (with sealing and pressure-proofing) and the
It is formed by a reactor protection structure (with sealing and pressure-tightening properties). The reactor pressure tank is made of steel or prestressed concrete, and the reactor protection structure is made of steel or concrete.

A nuclear reactor constructed like this is described in the German Federal Patent Publication No. 3.
It is known from No. 212322. In this type of equipment, the reactor protection structure is an important element from a technical safety point of view.
It is necessary to form a boundary for the secondary cooling system and to form a protective barrier against the influence to some extent to have the characteristics as a safety tank, and the manufacturing cost of these is very high.

In a high-temperature nuclear reactor with a prestressed concrete pressure vessel, a prestressed concrete pressure vessel with a large internal space for the installation and removal of reactor internal parts and for accommodating some of the parts. All components of the primary cooling system are housed in one or more housing spaces. The sealing of the primary cooling system in this internal space is achieved by a pressure-resistant and gas-tight airlock mechanism.

A nuclear reactor comprising a prestressed concrete pressure vessel with such an internal space and an aerodynamic mechanism is shown in German Patent Application No. 31 41 734. Each of these airlock mechanisms is formed from a double lid made of steel that is fitted into the internal space. The inner lid shuts off the primary cooling gas. In such devices, a hermetic reactor protection structure must be provided.

DE 15 64 783 likewise describes the use of a double lid as a protective barrier for the reservoir of a nuclear reaction pressure tank.

[Object of the present invention]

The object of the present invention is to provide a high-temperature gas reactor system having the structure described in the introduction, from the standpoint of profitability and technical purpose, by providing nuclear fission The goal is to reduce the cost of forming each barrier necessary to prevent product diffusion.

The above problem is solved by the following configuration according to the present invention.

a) A metal liner lining is provided as the third barrier of the fission product containment reservoir, and a concrete member of the prestressed concrete pressure vessel as the fourth and final barrier, both barriers being provided with two spares. It forms the boundary of

b) The sealing action of the third or fourth barrier in the internal space of the tank is achieved by an aerodynamic mechanism consisting of a steel double lid installed in this internal space in a known manner, and the inner lid of the double lid is It forms the primary Ganu section.

C) An intermediate section between the outer lid and the inner lid connects the leakage of the primary gas to the exhaust pipe through a filter structure to prevent the diffusion of fission products.

According to the present application, in order to reliably maintain the airtightness of the primary cooling system formed within the prestressed concrete pressure vessel, a structure with backup capability is used. A prestressed concrete pressure vessel has two preliminary boundaries: a metal live "and a concrete member with a particularly strong permeate flow-restricting effect. The amount of radioactive material penetrating through this concrete member is not critical to safety. If the amount of permeation exceeds the set value, it is determined that there is a leak in the liner, and the reactor is shut down.If the amount of permeation is less than the set value, the preliminary boundary of the concrete member is set to NR. The reactor is now operational again.

If there is a leak in one of the inner lids of the lock mechanism, the leaked primary gas will be released through the filter mechanism and the exhaust stack, and the fission products will be trapped within the filter. In the intermediate chamber between the inner lid and the outer lid, there is a negative pressure, and the outer lid reliably performs the role of sealing.

Therefore, the outer cover forming the fourth barrier has a reliability equivalent to that of the safety tank of the above-mentioned core system with a steel expanded reactor pressure tank.

There is no need for a separate hermetic safety structure, as radioactive materials in the primary cooling system will not leak into the surrounding area through the prestressed concrete pressure vessel or through the airlock mechanism in the space. Moreover, the task of reliably sealing the primary gas and ensuring the safety of the high-temperature gas reactor before external influences can be achieved can be accomplished uniquely by the prestressed concrete pressure vessel. By using an airlock mechanism equipped with an intermediate exhaust mechanism, unnecessary equipment costs that would otherwise be required can be reduced.

Therefore, the present invention does not require a reactor safety room, which is important in terms of safety engineering, so that a high-temperature gas reactor can be constructed economically.

In order to reliably prevent primary gas leakage, burying part of the pipe in the concrete of the prestressed concrete pressure vessel up to the exhaust stack connection has the effect of reducing the risk of leakage from this pipe. .

A filter system for preventing the diffusion of fission products can be installed inside the wall of a pressure vessel and can achieve the same effect as described above.

Prestressed concrete pressure vessels are equipped with safety devices to protect against airplane crashes. This safety device consists, for example, of a concrete chamber and serves as an architectural enclosure for the nuclear reactor. This concrete room does not need to function to prevent the leakage of radioactive materials in the primary cooling system, and can have a simple structure.

A cylindrical prestressed concrete pressure vessel 1 comprises a receiving space 2 lined with a metal liner 3. A high-temperature gas reactor 4 is installed in the accommodation space 2, and its core is formed by depositing spherical fuel. This fuel consists of coated fuel pellets and a graphite matrix. The graphite matrix and coating serve as the first and second barriers to prevent nuclear fission and diffusion.In this reactor core, cooling gas (helium gas) flows from top to bottom, as shown by the arrow in the figure. ) is flowing negatively. Further, this core is surrounded by a reflective material 5, and a high temperature gas collection chamber 6 is connected to the lower part of the reflective material 5. Above the hot gas channel 7 , a hot gas collection chamber 6 is provided with a plurality of steam generators 8 surrounding the hot waste 4 in the receiving space 2 . A plurality of transfer fans 9 send the low-temperature cooling gas back to the core. The reflector 5 is surrounded by a thermal shield 10 that limits the convection of cold cooling gas.

The prestressed concrete pressure vessel 1 is provided with a plurality of large internal spaces 11 at its ceiling, each of which is closed by an airlock mechanism 2. This internal space 11 is provided in a 6-round shape useful for assembling and disassembling the steam generator 8 and other reactor components, and the rotary transfer fan 9 is installed within this internal space 11. Each of the airlock mechanisms 12 consists of steel lids 13 and 14 facing each other, the inner lid 13 being one
It forms a waste cutoff section.

A tube 1 is provided between the lids 13 and 14 of each air lock mechanism 12.
There is an intermediate chamber 15 connected to 6. Most of this pipe 16 is buried in the concrete part of the prestressed concrete pressure vessel 1, and is connected to the exhaust pipe J8 through the filter 7 stem 17, thereby serving to prevent the diffusion of nuclear fission products. A filter 7 stem 17 is also provided inside the prestressed concrete pressure vessel 1 adjacent to the pipe 16 to reduce the risk.

According to the invention, instead of an extra reactor protection structure forming an outer barrier to prevent the diffusion of fission products, a prestressed concrete pressure vessel 1 as described above takes its place. are doing. This pressure vessel 1
The metal liner 3 forms a third barrier, in particular a gas-tight boundary. The concrete part forms the fourth outermost barrier. In other words, two backup boundaries are formed in the prestressed concrete pressure vessel 1. The part between the internal flights 1 and 2 is the aero ivy mechanism 2.
The inner lid and outer lid 14 form third and fourth barriers. Even if leakage gas flows into the intermediate chamber 15 through the inner lid 13, the outer lid 14 is formed to a size that provides a sufficient seal, but the intermediate exhaust mechanism of the pipe 16 requires complete airtightness. Therefore, due to its sealing effect, this outer cover 14 also serves as a reliable barrier. Therefore, a gas-tight reactor protection structure is not required.

[Brief explanation of drawings]

The drawing shows a longitudinal section of a high temperature source->furnace according to the invention. Details that are not material to the invention are omitted and misrepresented. l...i;, I? , stressed concrete pressure vessel, 2...accommodation year, 3...metal liner, 4...core, 5...reflector, 6 high temperature gas collection chamber, 7...high temperature gas channel, 8 ...Steam generator, 9...Time transfer fan, 10...Protection shield, 1...Inner space,
12... Air lock mechanism, 13... Inner lid, 14...
... Outer lid, 16° pipe, 17... Filter mechanism, 18... Exhaust pipe 0

Claims (4)

[Claims] (1) A high-temperature gas furnace using a spherical fuel consisting of fuel pellets embedded and coated within a graphite matrix, wherein the coating of the fuel pellets serves as a first barrier, and the graphite matrix serves as a second barrier. A prestressed concrete pressure vessel surrounding the high-temperature gas reactor is provided as a pressure-resistant containment vessel, the plurality of barriers forming a barrier to prevent the diffusion of fission products, and the pressure vessel having a metal liner therein. a) a metal liner (3) as a third barrier to prevent the diffusion of fission products, and as a fourth and final barrier; The concrete elements of the prestressed concrete pressure vessel (1) are provided, with both barriers forming two preliminary boundaries; b) in the part of the internal space (11) of the tank, as a third or fourth barrier; The sealing action is provided by a steel double lid CIJ provided in this internal space (11),
14), the inner lid (13) of the double lid forms a primary cooling gas boundary; The intermediate section (15) is connected to a tube section (16) that guides leaked primary gas to the exhaust stack (18) via a filter mechanism (17) in order to prevent the diffusion of fission products. A high-temperature gas furnace using spherical fuel characterized by the following. (2) Claim 1, characterized in that the pipe body part (16) is buried in the concrete part of the prestressed concrete pressure vessel (1) and extends to the connection part of the exhaust pipe (18). High-temperature gas furnace described in Section. (3) The high temperature gas furnace according to claim 1 or 2, wherein the filter mechanism is embedded within the wall of the prestressed concrete pressure vessel (1). (4) Bure, z) Rest concrete pressure vessel (1)
The high-temperature gas furnace according to claim 1, characterized in that the high-temperature gas furnace is equipped with preventive equipment so as to be protected in the event of an airplane crash.